The invention relates to an over-center hinge for furniture doors, having two hinge links articulated pivotingly in the manner of a quadruple pivot on a door part, on the one hand, and on a wall part constructed as an elongated mounting arm on the other hand, which upon swinging from the closed position to the open position is movable through a dead center position on one side of which it is biased in the closing direction and on the other side of which it is biased in the opening direction by the tension of the spring, the spring being provided in the space available between the hinge link pivot points on the mounting arm side and engaging, with at least one end, a prolongation of one of the hinge links which with the mounting arm pivot axis of this link forms a lever arm which is directed from the pivot axis such that, in the hinge-closed position, it is biased by the spring in the sense of a pivoting in the closing direction, and in the open position it is biased in the sense of a pivoting in the opening direction.
Such over-center hinges, which are biased by spring tension into two stable end positions, have the advantage that a door articulated to a piece of furniture by means of such a hinge will not remain open in intermediate positions, i.e., with the door half-way open, so as to be damaged by drawers disposed within the cabinet, such as for example drawers for pots or supplies, or kitchen appliances arranged so as to be pulled out from recesses in kitchen cabinets. Such an over-center hinge is known (German Offenlegungsschrift 21, 17 828), in which a V-shaped spring of springy strip or wire material is used for the production of the spring bias, the spring being so disposed that the apex of the V-shaped spring is wrapped around the pivot pin on the mounting arm end of one of the hinge links, while the free end of one of the legs of the spring engages a projection in the mounting-arm-end area of the other hinge link, while the second leg of the spring bears directly or indirectly on the mounting arm. The production of a sufficiently great spring force is difficult with such V-shaped springs on account of the small amount of space available, and the installation of the springs is expensive, especially when they are hairpin-like springs formed of steel spring wire spirally wound in several turns at the apex. In practice, over-center hinges of this kind have for this reason failed to become popular.